from PyQt5 import QtWidgets  
from PyQt5.QtWidgets import QMessageBox
from PyQt5.QtGui import QMainWindow  
        
class MyWindow(QtWidgets.QWidget):  
    def __init__(self):  
        super().__init__()  
        self.myButton = QtWidgets.QPushButton(self)  

        self.myButton.clicked.connect(self.msg)  
    
    def msg(self):  
        reply = QMessageBox.information(self,                         #使用infomation信息框  
                                    "标题",  
                                    "消息",  
                                    QMessageBox.Yes | QMessageBox.No)  
    
if __name__=="__main__":    
    import sys    
    
    app=QtWidgets.QApplication(sys.argv)    
    myshow=MyWindow()  
    myshow.show()  
    sys.exit(app.exec_())